Coat the insert of your slow cooker generously with non-stick cooking spray or use a crock pot liner.
In a mixing bowl, combine cream cheese, sugar, and eggs. (I usually mash it all together with a fork so there are creamy cream cheese pieces in the casserole. If you prefer the cream cheese completely mixed in, use a hand mixer and beat until smooth.)
Pour the cream cheese mixture along with the frozen corn, shredded cheese, creamed corn, cornbread mix, milk, diced jalapeno, melted butter, garlic powder, salt, and pepper into the slow cooker. Stir until evenly combined.
Cover and cook on HIGH for 2-3 hours. The center of the casserole should be set and have a very slight jiggle once it has finished cooking. (My casserole usually takes around 2.5 hours.)
Remove the cover and top with jalapeno slices if desired. Serve warm.